1. Technical Field
The present invention relates to a droplet discharge method, an electro-optical device, and an electronic device.
2. Related Art
The droplet discharge head of an inkjet printer is able to discharge microscopic ink droplets in the form of dots, which affords extremely high precision in terms of the uniformity of the size and pitch of the ink droplets. This technology has been applied to the manufacture of many different products, such as electro-optical devices. For instance, it can be applied in the formation of a film for the light-emitting components of organic EL display devices or the color filter layers of liquid crystal devices.
More specifically, a droplet discharge head is filled with a special ink, a photosensitive resin liquid, or another such functional liquid, and droplets of this functional liquid are discharged onto prescribed portions provided on a substrate. Japanese Laid-Open Patent Publication No. 2004-267927 is an example of related art. A number of different colors are usually formed in the light-emitting components or color filters used in conventional electro-optical devices, and a plurality of types of functional liquid are discharged onto the substrate, each by a different device, one at a time.
When the apparatus discussed in the above mentioned reference is used, however, since a plurality of types of functional liquid are discharged onto the substrate by different devices one at a time, the overall discharge process ends up taking a long time. In view of this, the idea was conceived to discharge all types of functional liquid with a single device in order to shorten the discharge time.
Also, the prescribed portions provided to the substrate usually have a larger volume than the droplets of functional liquid, and cannot be fully filled with functional liquid in a single scan, so scanning is performed a number of times. Further, since the prescribed portions have a large bottom surface area compared to the size of the droplets of functional liquid, in each scan the functional liquid is discharged evenly over the entire bottom surface of the prescribed portions so that the functional liquid will not be distributed unevenly within the prescribed portions.
However, as the functional liquid starts to fill the prescribed portions over a plurality of scans, the functional liquid newly discharged toward the prescribed portions can sometimes rebound upon hitting the surface. Particularly around the peripheral edges of the prescribed portions, any functional liquid that rebounds can splash out of the prescribed portions and may become mixed up with another type of functional liquid, such as the functional liquid held in an adjacent prescribed portion. Furthermore, if discharged functional liquid comes into contact with the top of the dividing walls that separate the prescribed portions, the functional liquid may rebound, or the functional liquid adhering to the top part of the walls may flow and become mixed with the functional liquid of another prescribed portion adjacent to the targeted prescribed portion. If functional liquids of different types become mixed in an electro-optical device, this can lead to a decrease in contrast. Also, even if functional liquids of the same type become mixed, the targeted prescribed portions may end up not holding the intended amounts of functional liquid, which causes density unevenness.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved droplet discharge method, an improved electro-optical device, and an improved electronic device. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.